Steganographic data hiding using a device clock

Abstract

The presently claimed invention relates generally to methods and apparatus associated with steganographic encoding (e.g., data hiding). One claim recites a method including: obtaining plural-bit auxiliary information; and during communication between a first computer and a second computer over a network, modulating timing or phase of a clock signal generated by the first computer so as to steganographically hide the plural-bit auxiliary information in a communications signal sent between the first computer and the second computer. Of course, other claims and combinations are provided as well.

What is claimed is: 
     
       1. A method comprising:
 obtaining plural-bit auxiliary information; and 
 during communication between a first computer and a second computer over a network, modulating timing or phase of a clock signal generated by the first computer so as to steganographically hide the plural-bit auxiliary information in a communications signal sent between the first computer and the second computer. 
 
     
     
       2. The method of  claim 1  wherein the clock signal comprises a system clock signal generated by the first computer. 
     
     
       3. The method of  claim 2  wherein the signal is varied in accordance with the plural-bit auxiliary information. 
     
     
       4. The method of  claim 3  wherein a period of the signal is varied in accordance with the plural-bit, auxiliary information. 
     
     
       5. An apparatus comprising:
 an input or memory to receive plural-bit auxiliary information there from; 
 a signal generator; 
 an output to communicate with a different apparatus over a network, the output communicating a clock signal generated by the signal generator, the signal generator modulating timing or phase of the clock signal so as to steganographically hide the plural-bit auxiliary information in the signal. 
 
     
     
       6. The apparatus of  claim 5  wherein the signal generator comprises a system clock, and the signal comprises a system clock signal. 
     
     
       7. The apparatus of  claim 6  wherein the signal is varied in accordance with the plural-bit auxiliary information. 
     
     
       8. The apparatus of  claim 7  wherein a period of the signal is varied in accordance with the plural-bit auxiliary information. 
     
     
       9. The apparatus of  claim 5  in which the signal generator is operating to modulate timing or phase of the signal so as to steganographically hide the plural-bit auxiliary information in the signal. 
     
     
       10. A programmed computing device storing instructions in memory, said instructions are executable by said programmed computing device to perform the acts of  claim 1 . 
     
     
       11. A computer readable media comprising instructions stored thereon to cause a multi-purpose computer processor to perform the acts of  claim 1 .